Low tension ignition systems



March 20, 1956 J. K. DELANO LOW TENSION IGNITION SYSTEMS 5 Sheets-Sheet 1 Filed July 18, 1951 INVEN TOR. Jfl/VEJ' A. DELA/VO March 20, 1.956 J. K. DELANO LOW TENSION IGNITION SYSTEMS 5 Sheets-Sheet 2 Filed July 18, 1951 IN V EN TOR.

2%J/WM March 20, 1956 J. K. DELANO LOW TENSION IGNITION SYSTEMS 5 Sheets-Sheet 3 Filed July 18, 1951 mm m INVENTOR. Jfl VEJ' I). DELflA/Q flTTORNEY March 20, 1956 J. K. DELANO 2,739,178

LQW TENSION IGNITION SYSTEMS Filed July 18, 1951 5 Sheets-Sheet 4 INVENTOR. JZ'MEJ' f'f. DEZfl/VO March 20, 1956 Filed July 18, 1951 5 Sheets-Sheet 5 INVENTOR. Jfl/VES K. DELANO fiTTOR/VEY LOW TENSION IGNITION SYSTEMS James Kendall Delano, Rye, N. Y. Application July 18, 1951, Serial No. 237,403 2 Claims. (Cl. 123-148) This invention relates to a low tension dual ignition system suitable for a multi-cylinder radial engine and particularly to a dual distributor thereof.

The construction of an ignition distributor system for multi-cylinder engines becomes a substantial mechanical and electrical problem when the cylinders become numerous. In many instances, it requires several magnetos with their respective mechanical drives and mountings to supply the ignition. To adjust the several magnetos to operate accurately in proper phase relationship, so they will coact together, is a very accurate and painstaking job for a skilled mechanic.

There is also the engines construction that must be considered, especially the radial type that employs a master connecting rod. This type of engine does not fire its cylinders at exact sequence so the compression peaks do not occur at exact regular intervals. Hence it re quires a special cam for the interruption of the magneto contacts.

The object of this invention is to provide a compact, easily installed ignition system construction that is light in weight, that can be accurately tuned to engines of 18 to 24 or more cylinders, and that has the advantage of being adjustable to fire each cylinder exactly at the point where highest efiiciency may be achieved. An advantageous feature of the system is that a complete failure of one of the component elements will not aitect the remaining elements, so the engine will continue to operate even though with reduced horse power. The greatest wear in present ignition systems is at the contact points that make and break the primary circuits. In the present invention there is no arcing or electrical wear as the contacts handle a predetermined amount of current and do not break the circuits where current is flowing through the contacts. Only after the current ceases to flow do the contacts separate. The life of the contacts is thereby greatly increased. Frequent adjustment and resetting of the contact points in service is therefore obviated.

The system operates on the charging and discharging of a condenser circuit. The system may, therefore, be operated at extremely high speed.

The supply voltage is low enough so that corona losses are negligible. Any D. C. source of supply may be used, such as a radio tube plate voltage, a rotary converter, a diode tube, a vibrator rectifier, or other similar sources, the current consumption being extremely small.

One object of this invention is to provide an ignition system in which low voltage energy may be distributed from a control distributor to the spark plugs, and the voltage then stepped up at the spark plugs to the ignition voltage required to ignite the compressed gas charge in the cylinder.

Another object of this invention is to provide a system in which an independent circuit is employed for each individual cylinder. This will enable the engine to operate in case of the failure of the components for one or two cylinders, as distinguished from the conventional systern wherein the failure of an ignition component would nited States Patent cause a failure of the entire ignition system and prevent any operation of the engine.

Another object of the invention is to provide a system in which the ignition circuit to each cylinder may be independently timed.

Another object of this invention is to provide a system in which a uniform amount of energy is delivered to the spark plugs regardless of the engines speed, thereby contributing to the regularity of operation of the plugs.

Another object of the invention is to provide an ignition system including an automatic spark advancer and retarder.

Other objects and features of this invention will be apparent upon reference to the accompanying drawing and description, in which:

Fig. l is a schematic elevational outline of an airplane engine to which the ignition system of the present invention is shown applied;

Fig. 2 is a plan view of a double distributor unit of this invention;

Fig. 3 is a front view of the mounting plate as viewed in the direction of arrows 3-3 of Fig. 2;

Fig. 4 is a side view, partially in elevation, with parts broken away to show'a vertical sectional view of one distributor unit together with the automatic spark advancer which operates to control both distributor units;

Fig. 5 is an end view, partially in elevation and with a portion of the cover broken away to show a vertical section of one of the distributor units, taken in the direction indicated by the arrows 5-5 of Fig. 4;

Fig. 6 is a vertical sectional view taken in the direction of the arrows and along the line 66 in Fig. 4, resulting substantially in an elevational view with the cover removed;

Fig. 7 is a plan view of the automatic spark advancer device taken through a sectional cut of Fig. 8;

Fig. 8 is a vertical se tion taken along the line 8-8 of the spark advancer unit otherwise shown in Fig. 7; and

Fig. 9 is a plan View of portions of the spark advanccr taken along the line 99 of Fig. 8, to show the gear type coupling between the adjusting weights and the intermediate coupling shaft between the drive shaft connection and the driven shafts of the two distributor elements.

Fig. 10 is an enlarged sectional view of the distributor cam and a pair of ignition circuit switches;

Fig. it is a plan view of the distributor cam and some or" the switch-operating push rods controlled by the cam;

Fig. 12 is a perspective view of a section of the guide support for the switch-operating push rods; and

Fig. 13 is a schematic diagram of the ignition system and circuit for one spark plug.

As shown in Fig. 1, an air plane engine It) is provided with a dual ignition system of the present invention, of which certain components of the system are shown, including a dual distributor unit 12 arranged to be driven at an appropriate speed from the main shaft of the engine through suitable gearing 13, and a driving connection 14-. with an electrical conduit system indicated by a pipe 15 and a cable manifold 16 for the multi-conductor cables 17 for connection to the individual spark plugs 18, that are shown in this case as being self-complete to receive low-voltage energy pulses and to transform them into highvoltage energy pulses to ignite the gaseous mixtures compressed in the cylinder heads.

The entire ignition system is shown completely shielded metallically by means of its enclosing housing and the metallic conductors 15 and 16. The ignition cables that extend beyond the manifold 16 to the plugs 18 are preferably provided with suitable braided metallic shielding which is grounded at one end on manifold 16 and the metallic engine structure, and proceeds at the other end to the input terminal of the spark plug, thereby to insure a completely grounded shielding for the entire ignition system, that will prevent any interference with any of the radio equipment that might be carried on the plane.

As shown in Fig. 2, the distributor unit 12 comprises two separate distributor units, respectively enclosed in two separate housings 21 and 22 integrally mounted on a common base 23, through which driving energy is delivered to the distributors on a common drive shaft 24, to which a suitable driving connection may be made to the engine shaft, as indicated .by the gearing 13 and shaft 14 of Fig. 1.

Each distributor unit 21 and 22 is shown provided with multi-point connectors 25 and 26 to permit ready connection and disconnection of the distribution cables and t e distributors. The two plugs 25 and 26 are appropriately covered on the outside with a form of metal conductor which will contact the metal of the housing and the metal of the conduit 15 that contains the low voltage distribution cable. The housing for the double unit is otherwise designed and shaped at its common back structure to permit the combined unit to be mounted on the customary mounting plate 28 usually provided to support and mount a conventional magneto for a conventional ignition system.

The mounting plate is shown in .Fig. 3 and needs no further description.

4 shows the general construction and arrangement of the elements of one distributor 21. The distributor 21, as shown, is provided with eighteen circuits, one for each cylinderof the engine. Each circuit includes a contact assembly 3%, a condenser 31 and a resistor 32. For convenience of illustration, the resistor 32 that is shown is the one related to the contact unit at the top of the figure. The electrical relationship between the contact unit 3% and the condensor 31 and the resistor 32 is illustrated in more detail in Fig. 13.

in order to control theoperation of the contact switches in sequence, a rotatable cam driving head 33 with a hardened camis provided to ride against and operate the radial pusher rods 34 respectively provided for each of the contact units 30. The operation of the distributor will be better appreciated after consideration of the description of the construction of the unit whereby the cam is operated to progressively actuate the distributor contact units.

Each distributor 21 and 22 comprises a main supporting mem er 4%) of substantially spool shape, having a bottom flange 45-1, a top flange :42, a central cylinder or sleeve 43 joining the two flanges 41 and 42, and a co-axial annular ring portion 44 on bottom flange 41 to receive and mount a bail bearing 45 to rotatably support one end of a distributor drive shaft 46, the other end of the distributor drive shaft 46 being supported in a ball bearing 47 set in a recess formed in the top flange 42 at the end of the connecting sleeve 43. An extension 48 on the outer end of the drive shaft 46 accommodates and supports the cam 3-3 which is secured to the shaft extension 48 by a key 49, and a lock washer and nut assembly 59 which secures the cam against undesired separation from the shaft.

The cam driving head 33 is substantially concentric except for a small cam disc 52 supported thereon which establishes the camming action against the contact push rods 34. The cam disc 52 is held in fixed position at the periphery of the cam driving head 33 by a clamping screw 53, which may be loosened, when desired, to permit the cam disc 52 to be turned to a new position and reclamped to present a new wearing surface to actuate the push rods 34. As shown in Fig. ll, the peripheral surface of cam disc 52 extends radially slightly beyond the periphery of the cam driving head 33.

The push rods 34 are "made of insulating material, such as Micarta, a linen impregnated with Bakelite, or similar material, and are seated and guided in radial milled slots 56, Fig. 6, in a heat-treatednickel steel annular ring 55 that is co-axially seated on the outer flange 42 of the main spool-shaped supporting bracket 43. The pusher rods 34 operate freely in the milled slots 56 within close limits.

A supporting structure 60 of insulating material, such as Bakelite, is mounted on and anchored to the top flange 42 of the main spool-shaped supporting bracket 43, and serves to support the contact units 30 of the distributor in a circle, concentric with the axis of rotation of the shaft 46 for the cam. The insulating supporting structure 5% comprises a cylindrical sleeve body 61, a flange 62, and a head section divided into two concentric annular rings 63 and .64. The lower, inner end fill-a of the cylindrical body 61 supports an inner annular ring 66 of insulating material such as Bakelite.

The entire insulating block structure 60, which carries the distributor contact assemblies 30 and the resistors 32, is thus mounted and supported as a unit on the main supporting member 49, concentric with the axis of rotation of the drive shaft 46 for the cam.

At this stage of the description, it will be more advantageous to consider the operation of the system by reference to Figs. 10 and 13.

As illustrated in Fig. 13, two alternate sources of direct current are indicated as suitable to supply charging energy for each of the condensers 31, which will be subsequently discharged to supply ignition energy to the spark plug associated with that specific individual ignition circuit. By way of illustration, a motor-generator set 70 is illustrated as drawing energy from a storage battery 71 to drive a motor 72 at the low voltage of the battery in order to drive a generator 73 to provide direct current charge to the condensers 31 through their respective charging resistors 32 and associated fuse 74. Alternatively, an alternating current may be rectified by a suitable diode tube 75 to supply rectified pulses to the condensers 31 through their resistor 32 and their associated distributor contact switch 30. A selector switch 76 will be employed where both sources of supply might be available, in order to permit either source to be selected. Obviously, any other suitable source of direct current energy may be employed.

The distributor contact assembly 34) (Figs. 10 and 13) comprises an adjustable stationary back contact 80, a transfer contact 31, mounted on a resilient spring element 82, and a front transfer contact 83 mounted on the same spring element 82 is disposed to engage stationary front contact 84 on a spring element 85 after disengagement of back contacts 80 and 81.

The stationary back contact 80 is mounted on the front end or tip of the adjustable screw whose head end provides a terminal connection for that contact.

The back contact 81 on the spring element 82 is normally biased toward the stationary contact 80, and is disengaged from that contact 80 whenever the asso ciated push rod 34 is actuated by the cam disc 52. immediately after the opening of the back contacts 80 and 81, the transfer contact 83 engages the stationary front contact 84 to close the ignition circuit. The spring element 85 that supports the stationary front contact 84 is anchored at one end .on a terminal pin or bolt 86, and so formed as to bias the front contact 84 toward the transfer contact 83. The forward movement or position 'of the leaf spring 85 is determined and limited by a stop finger 67 which has its lower end anchored on the same bolt 86 and is adjustable by a screw 88 to position the forward face of the stationary front contact 84. By means of the two adjusting screws '85 and 88 the relative timing of the engagement between the contacts 83 and 84, to close the ignition circuit, may be controlled Within a short range.

As shown in the diagram of Fig. 13, the voltage from the generator 73 or from the diode tube 75, as selected by the switch 76, energizes a common bus line 77 which serves as a common supply line to energize all of the condensers of the distributor system. Each condenser 31 is supplied through its own resistor from the common supply line 77. The diagram illustrates one complete charging circuit from the supply line 77, through the resistor 32, the fuse 74 and back contacts 80 and 81 to the condenser 31, and then an ignition discharge circuit from the condenser 31 through front contacts 83 and 84 to its associat d spark plug 18. Similarly, another similar ignition circuit is energized through its resistor 78, and still another circuit is energized through its resistor 79, and so on. Only the supply circuit represented by the bus line 77 is common to all the ignition circuits. Otherwise, each ignition circuit has its own charging resistor and storage condenser 31, and its own discharge spark plug 18 to be energized from its associated condenser.

The spark plug that is utilized in this low voltage distribution system comprises briefiy a primary winding 91, a secondary winding 92 with an appropriate magnetic circuit generally indicated by the core 93, but actually including the complete magnetic shell to provide an extremely eificient transformer action between the two windings. One terminal of the secondary winding 92 is connected to one terminal of the primary, and that common terminal is grounded on the engine block. The high voltage terminal of the secondary winding is connected to the arcing electrode of the spark plug, the other terminal of the spark plug being grounded on the engine block in the customary manner. The ground connections indicated in the diagram of Fig. 13 represent a common connection through the engine block, which serves as ground for the system.

The specific construction and details of operation of the spark plug 18 are described and claimed in my copending application, Serial No. 231,769, filed June 15, 1951, now Patent.N0. 2,632,132.

The connections of the contact switch unit of Fig. may now be more clearly designated with reference to the diagram of Fig. 13. The bottom of the leaf spring element 82 is supported and anchored on the insulating ring 66 by a bolt 95 which serves also as a terminal for connection of the conductor 96 that proceeds to one terminal of the associated condenser 31 of that particular ignition circuit. A bent bracket 97 at the lower end of the leaf spring element 82 serves to hold the leaf spring vertically and to prevent its rotary movement on the bolt 95. The bolt 86, which anchors the lower end of the leaf spring 85 for back contact 84, serves as a terminal for a conductor 98 to the associated spark plug 18.

The electrical connection within each ignition circuit may be readily understood upon reference to Fig. 13. In a normal rest position of the distributor contact unit 30, as illustrated in Fig. 13, and as shown by the right-hand contact 343 at the top of Fig. 10, the transfer contact 81 is engaged by the back contact 80 to complete a charging circuit from the common supply bus 77 through the resistor and fuse, through the two contacts 80 and 81, the leaf spring 82 and its anchoring terminal bolt 95, thence through the conductor 96 to one terminal of condenser 31, the other terminal of which is grounded and thus connected to the other terminal of the supply circuit.

The time required for the condenser 31 to receive substantially full charge is a function of the time constant of the circuit, as controlled by the capacity of the condenser and the value of the resistor 32, in accordance with well known theory. Accordingly, the proper value of the resistor 32 will be determined by the capacity of the condenser 31 and the time available between successive charges of the condenser. The condenser may be assumed to be fully charged by the time the cam 33 is rotated to a position where its cam disc will engage the pusher rod or finger 34 to separate contacts 80 and 81. Since the condenser voltage is substantially equal to that of the charging bus 77, the two contacts 80 and 81 are substantially of the same potential upon separation, and there will be no voltage differential between the contacts that would attempt to establish a spark at the separating contacts.

Immediately after separation of back contacts and 81, front contacts 83 and 84 are engaged to close the discharge circuitfrom condenser 31 to the spark plug 18. The condenser 31 immediately discharges its stored energy into the circuit including the primary winding 91 ofthe transformer at the spark plug, at a time rate that is again a function of the time constant of that circuit, including the capacity of the condenser 31 and the inductance of the primary winding 91. The condenser discharge current through the primary winding induces a high voltage in the secondary winding 92 which is sufficient to cause a spark across the gap of the spark plug sufiicient to ignite the surrounding compressed gaseous charge that has been formed in the associated cylinder of the engine.

No arcing occurs at the contacts. When the circuit to the condenser is opened at contacts 80 and 81, the condenser is fully charged and at the some voltage as its source, so no potential difference exists between the separating contacts 80 and 81. Closure of contacts 83 and 84 causes no arcing, since current is not interrupted. Subsequent separation of contacts 83 and 84 also causes no arcing since the condenser is already discharged.

In order to clear any ignition circuit in which a condenser may become short-circuited, a therniofusible link 74 is provided in each ignition circuit. In one form, the fuse may be merely the soldered connection alone at the resistor terminal, to serve as a fusible link through which an external conductor is connected to the resistor, the conductor being otherwise not mechanically secured to or hooked on the terminal. In another form, the fusible link may be a separate fusible wire in series with the resistor and wound around the resistor. In still another form, the fusible link may be disposed adjacent the resistor body to conduct two halves of the resistor 32, 73, or 79, and be insertable at the time of manufacture of the resistor, or later. Thus, the resistor 32, for example, which may be of the order of 15,000 ohms, would be made up of two sections, each 7,500 ohms, with a fusible link connecting the two inner terminals.

The function of any thermo-fusible link 74 is to interrupt its associated circuit in the event that the condenser in that circuit should become short-circuited. Such a condition would be attended by excessive current through the associated resistor, with consequent rise in temperature in the resistor.

Under normal conditions, the time required to charge a condenser is relatively short. The current through the resistor is correspondingly of short duration, and in fact, diminishes from its initial value to a low value, as the condenser charges. Therefore, under normal conditions, the resistor heating is inappreciable. When the condenser is shorted, however, it becomes an impedance of low resistance and accepts a continuous current from the supply source. That continuous current through the resistor soon raises the temperature of the resistor to a value sufficient to melt the thermo-fusible link and thereby open the circuit to cut off the short circuited condenser. The fusible link should be disposed close to the resistor, to be affected by heat conducted or radiated from the resistor. The fusible link may be formed of any suitable low temperature alloy. Thus, the section of the fusible link need not be extremely fine as it would need to be to rely upon the small change in current when the condenser input impedance dropped from its maximum value, during normal condition, to a low value when short-circuited.

Since the cam is driven from the engine shaft and in synchronism therewith, the cam operates upon each ignition contact unit 30 in progressive sequence to ignite the charges in the respective engine cylinders in proper progressive time relation.

In order to provide for increased efficiency at the higher speeds of the engine, it may be desirable according to the characteristics of the engine to which the system may be applied, to advance the spark timing slightly with the respect to the engine stroke. For that purpose, an automatic spark advancer or governor 100 is provided in the mechanical connection between the drive shaft 24 and the distributor shaft 46, to provide a variable advance in the timing position of the cam 33 in accordance with the speed of the main engine shaft as impressed upon the drive shaft 24 forthe distributor herein disclosed. a

It is advantageous to have the spark as far advanced as possible to get full efliciency from the engine. With ordinary magnet-o operation the spark is setto fire a full cylinder position either retard or advance, and the operator is required to shift the ignition phase positions when starting or running. 'When the ignition is set to advanced phase position roughness of operation is caused when the engine is throttled below full flying speeds. With the advancer mechanism shown, this is entirely overcome, as the governor will retard the spark for starting or for idling speed and will advance the spark when engine speed requires it. No attention is required by the operator.

The spark advancer or governor 100, as shown in 'Fig. 4, or in more detail in Figs. 7 and 8, comprises a supporting drive plate 101 carrying two pivotally supported fly-weights or governor weights 102 and 103, respectively provided with arcuate sections 104 and 105 to mesh into a gear section 106 to angularly adjust a governor sleeve 107 against a restraining bias force of a helical spring 108 and to selectively position a pinion gear 109 that meshes with and drives a bevel gear 111 supported on and keyed to the cam driving shaft 46, Fig. 4.

The bevel gear 111 is suitably secured to the cam drive shaft 46 by a pin 112.

in order to drive the corresponding cam shaft 46-a of the distributor 22 by means of the same bevel gear 111, the bevel gear 111 is provided with a split sleeve 113 having an extended semi-circular portion 114 disposed to extend over the adjacent end of the drive shaft 46-11 for the cam of distributor 22, in peripheral seating engagement with a similar extension 114-11 of a sleeve 115 fitted over and secured to the end of the drive shaft 46-11 for the cam of distributor 22.

By means of a single bevel gear 111 the two drive shafts and. 46-a for the two cams of the respective distributors 21 and 22 may be simultaneously and Synchronously driven. The two sleeve sections 115 and 114 may be each selectivelypositioned on their respective drive shafts 46 and 46-a and then securely fixed to their respective shafts by a pin or positioning screw 112 for sleeve 114 and a similar pin or positioning screw 116 for the sleeve 115.

As shown in Fig. 4, the drive plate 101 is suitably secured to the drive shaft 24 by a key or the like, and the shaft then extends upward to provide an outbearing support 113 for the sleeve 107 and the bevel pinion gear 3109 supported on that sleeve. A roller bearing 120 is suitably supported on the housing structure to provide a confined rotating support for the gear sleeve 107 while at the same time maintaining a relatively rigid support for that sleeve, to eliminate any play or lost motion due to looseness.

The action of the governor may be readily appreciated upon reference to Figs. 7, 8 and 9. The two governor weights 102 and 103 are pivotally supported on pins 121 and 122, both of which are anchored in the drive plate 101. A gear segment 123 provided with gear teeth 104 is concentrically disposed on the same pin 121 and is fixed in position on the governor weight 102 by a pin 12.4. A similar arcuate segment 125 carrying the teeth 105 is concentrically disposed on the pin 122 and keyed in fixed position on the governor weight 103 by a pin or rivet 126, and, thereafter, when the drive shaft 24 rotates the .drive plate 101, the two fly weights or governor weights 102 and 103 are revolved around the central axis and shaft 24 and extension 118, and the'two weights 102 and 103 are influenced by centrifugal motion to move their free ends radially outward from the extension 118 of'drive shaft 24, and respectively to move angularly around their own centers, or pins 121 and 122 respectively. The two fly weights 102 and 103 move out to positions controlled by the speed of rotation of the drive shaft 24 and the counteracting force of the helical tension spring 108, that reacts on the two weights 102 and 103 by suitable stops 128 and 129, anchored on the drive plate 101.

The helical spring 108 has one end anchored on the anchor .pin 131 secured to the drive plate 101, and the other end of the spring is held by threaded anchoring bolt 132 fitted into and fixed in gear sleeve 107. V

By means of the system disclosed herein, a simple, rugged, and reliable ignition system is provided, that may be easily adjusted and serviced, but that is inherently stable and free of trouble possibilities. The provision of the automatic spark advancer contributes to the smoothness and efiiciency of the engine to be controlled thereby.

What is claimed is:

l. A dual ignition distributor for multicylinder engines comprising 'a mounting plate, an input drive means journalled in said mounting plate and having a pinion gear on its innerend, separable dual distributor heads secured to said mouting plate in opposing relationship to one another and extending at an angle to said input drive means, each of said distributor heads having a main supporting member having a sleeve portion and top and bottom flanges extending radially outwardly therefrom, a drive shaft extending through the sleeve portion and journalled therein, a plurality of individual condensers mounted about said bottom flange, cam means fixed to said shaft and lying adjacent to the top flange, an insulating block structure mounted over said top flange, a plurality of individual transfer switch devices mounted about the cam means and respectively wired to the respective condensers, and radially-extending push rods slidably mounted in the supporting member to operate respectively the respective transfer switch devices and engageable in sequence by the cam means, said drive shafts being axially aligned with one another, coupling means joining together said drive shafts and a gear mounted on one of said drive shafts and meshing with said pinion gear to be driven thereby.

2. A dual ignition distributor for multicylinder engines as defined in claim 1, and said input drive means having a drive shaft, a drive plate fixed to said drive shaft, sleeve means mounted on said drive shaft for rotatable adjustment with respect thereto, governor weights pivotally mounted upon said drive plate and connected to the sleeve means to rotatably adjust the same upon the drive shaft inresponse to the speed of rotation thereof, and a return spring connected between the sleeve means and the drive plate, said pinion gear drivingly secured to said sleeve means.

ficferences Cited in the file of this patent UNITED STATES PATENTS 1,674,152 Andrew June 19, 1928 2,125,035 Smits July 26, 1938 2,180,358 Hooven Nov. 21, 1939 2,426,784 Messerschmidt Sept. 2, 1947 2,474,550 Short et al June 28, 1949 2,490,960 Hanc'hett, Jr. Dec. 13, 1949 2,587,780 Smits Mar. 4, 1952 

